Because improved drug formulations showing, for example, better bioavailability or better stability are consistently sought, there is an ongoing need for more fully characterized, new, polymorphic and derivative forms of drug molecules. Characterization of tetrahydro-N,N-dimethyl-2,2-diphenyl-3-furanmethanamine hydrochloride, and crystalline polymorphs and a metabolite of tetrahydro-N,N-dimethyl-2,2-diphenyl-3-furanmethanamine hydrochloride are described herein toward this end.